FIG. 1 shows a generic description of a broadband network for providing telephone, internet and TV/video services to subscribers in a number of locations. A series of service providers provide the various services (SP1, SP2, SP3) to the network 10 via conventional access points 12. The network 10 provides connection to these subscribers via routers 14 located close to the subscribers. The subscribers can include business locations that can include routers in commercial property 16, and domestic subscribers with routers located in a central office 18 for a neighbourhood of separate dwellings (houses 17), or in a single building 19 such as an apartment. A network operator manages the network function by the use of a control and provisioning system 20. The present invention is particularly applicable to such networks.
For the function of the control and provisioning system 20, the network can be considered in an abstract way as comprising a core 22 having one or more cells 24, each cell having one or more network elements 26 as is shown in FIG. 2. Subscribers 28 connect to the network elements 26. This structure is not to be confused with the physical elements making up the network. The functional blocks 22, 24, 26 may be wholly or partly resident in the same or different physical elements, depending on the exact size and makeup of the network in question, although typically, each network element 26 will comprise a router. The subscribers (network clients) can comprises a PC or other connected network device.
Internet Protocol (IP) is the common form of communication used in most networks. Data communication using IP relies on addressing for the various parts of the network to be able to communicate with each other. An IP address (Internet Protocol address) is a unique address that certain electronic devices use in order to identify and communicate with each other on a computer network utilizing the Internet Protocol standard (IP). Any participating network device—including routers, computers, time-servers, printers, Internet fax machines, and some telephones—can have their own unique address.
IP addresses can be static or dynamic. A static IP address is one in which a device uses the same address every time a user logs on to a network. With a static IP address, a computer's identity can be easily identified by others, and users can easily connect with it. Such an approach is commonly used for websites, email servers and the like.
A dynamic IP address is one in which the address is assigned to a device, usually by a remote server which is acting as a Dynamic Host Configuration Protocol (DHCP) server. IP addresses assigned using DHCP may change depending on the addresses available in the defined pool assigned to that server. Dynamic IP addresses are used because they provide efficient use of a limited pool of available addresses. When there is no need to assign a specific IP Address to each device, users can simply log in and out and use the network without having to have previously obtained an assigned IP address.
The Dynamic Host Configuration Protocol (DHCP) is a set of rules used by communications devices to allow the device to request and obtain an IP address (and other parameters such as the default gateway, subnet mask, and IP addresses of DNS servers) from a server which has a list of addresses available for assignment. The DHCP server ensures that all IP addresses are unique, e.g., no IP address is assigned to a second client while the first client's assignment is valid (i.e. its ‘lease’ has not expired). Thus IP address pool management is done by the server and not by a human network administrator.
The procedure by which an IP address is obtained from a DHCP server is shown schematically in FIG. 3. Before it is possible for a client C to obtain an IP address, it is necessary to configure the router R to which it is attached (step 0). The router R can be configured in the factory (as is the case in many home routers) or can be manually configured by either downloading a configuration file or by connecting to the router by telnet and configuring the code operating the router. Whichever way is used, the configuration is essentially static and includes identification of the DHCP server extDHCP to use for IP address assignment.
On connection to the router R, the client C requests an IP address by sending a DHCP discover message (i) to the router R. On receipt of the DHCP discover, the router R relays it on to the network, including the DHCP server extDHCP (ii). The DHCP server responds to this message by issuing a DHCP offer (indicating that an IP address is available to meet the request) which is communicated to the router R (iii) and is in turn, relayed to the client C (iv). On receipt of the DHCP offer, the client issues a DHCP request to the router R (v) which in turn is relayed to the network (and DHCP server) (vi). The DHCP server assigns a particular IP address and issues an acknowledgement, including the assigned IP address (vii) which in turn is relayed by the router R to the client (viii). Steps v to viii are repeated periodically to maintain the lease to that IP address while the client is connected. In the event that the client disconnects (or is timed out), the IP address is released and steps i to viii must be repeated again to obtain a new IP address.
The static configuration of the router makes it difficult for the network to adapt to the changing needs of the clients.